We seek to understand the molecular basis of morphogenesis, that is, the process by which organisms realize their final form. As a model system, we will study the morphogenesis of the male copulatory bursa of the nematode Caenorhabditis elegans. This system is particularly well- suited for the study of morphogenesis because of the facility of genetic analysis in C. elegans and because its entire development can be directly and continuously followed in living animals. Understanding the molecular basis of bursal morphogenesis will be of general relevance because this process involves fundamental mechanisms (e.g., neuronal wiring, cell migration, secretion of extracellular structural material, etc.), defects in which can result in human disease. We will undertake a genetic analysis of bursal morphogenesis. Our goal is to identify genes (and their products) involved in coordianting cell- cell interactions in space and time. The proposed research includes a detailed analysis of two genes, mab-10 and mab(ct109), that have been implicated from our preliminary studies to be involved in temporal regulation and cell-cell interaction, respectively. We will also isolate and characterize additional mutations that perturb bursal morphogenesis. These mutants will be identified by screening for male infertility or by using a novel screen based on our recent identification of bursa-specific surface markers.